Flare for burning gas

ABSTRACT

Flare for burning by-product gas comprises caisson and means for holding said caisson in a partially immersed position.

United States Patent Genini et al.

FLARE FOR BURNING GAS Inventors: Maurice Genini, Creteil; Isaac [56]References Cited Behar, Paris, both of France UNITED STATES PATENTSAssignee: Societe anonyme dite: Coflexip, gfi t l 1 3830 b 2 leuX C cl 4i Malmalson France 3,666,395 5 1972 Kubasta 431/202 Filed: Mar. 21, 1974AppL NO: 453 428 Prinuzry Examiner-Edward G. Favors Attorney, Agent, orFirm-Brisebois & Kruger Foreign Application Priority Data [57] ABSTRACTMar. 22 1973 France 73.10246 Flare for burning byproduct g ComprisesCaisson u.s. Cl. 431/202; 9/83; 61/465 fii gffi fig Pamauy Int. Cl. F23D13/20 Field of Search 431/202; 9/83; 61/465 9 Claims, 8 ng FiguresPATENTEU 2 9 5 3,902,843

sum 2 nr 3 PATENTED SEP 2 75 saw 3 of s FLARE FOR BURNING GAS In theexploitation of oil fields it is frequently necessary to provide a flarefor burning the gas after it has been separated from the oil.

The present invention relates to a flare of the semiimmersed type whichis adapted to burn gas in installations for exploiting or treating oilbeneath the sea or in fresh water of substantial depth.

The present invention relates to a semi-immersed flare which is mountedon a caisson which assures the flotation of the flare but is heldbeneath the water so as to shelter the flare from the effects of thewave action. with only the upper part of the flare remaining above thewater.

The semi-immersed flare according to the invention has a particularlysimple and economical construction and it may be put in place andmaintained easily even when it is located in deep water.

The object of the present invention is to provide a new article ofmanufacture which consists of a semiimmersed flare characterized by thefact that the chimney of the flare is mounted on a caisson which isconstantly immersed but which has a positive buoyancy and is connectedto a base which is resting on the ocean floor through at least oneflexible tube under tension. The caisson is also connected to the baseby means of at least two anchoring and guiding cables which are normallysleek but which may be placed under tension in order to avoid tension onthe flexible tube or tubes. These cables also make it possible to mountor replace flexible tube or tubes.

In accordance with the invention. the flexible tube or tubes used arepreferably of the type comprising metallic reinforcing means whichresist radial pressure and longitudinal tension and comprise at leastone fluid tight sheath.

Advantageously the lower part of each flexible tube is provided with anautomatic connector which permits the automatic connection of the lowerpart of the flexible tube to a connector mounted on the base. Theconnectors or connector mounted on the base themselves connected byother steps to the reservoir or to the place at which the gas to beburned in the flare is sepa rated.

In a preferred embodiment of the invention the caisson comprises adevice which makes it possible to ballast it. that is to say. toregulate its buoyancy to exert on the flexible tube or tubes any desiredlongitudinal tension.

In accordance with the particular cmodiment of the invention. thebalancing means is mounted on the lower part of the caisson in such away as to hold it in a substantially horizontal position and thus avoidany possibility that the chimney of the flare will incline too greatlyaway from the vertical under the effect of the current or the wind.

In the simplest embodiment a semi-immersed flare comprises a singleflexible tube which connects the caisson to the base.

In the more complex embodiments several parallel fle\ible tubes may belocated between the caisson and the base which make it possible toinsure that a larger volume of gas will flow toward the chimney.Moreover. it is possible to replace one of these tubes while the othercontinues to supply the flare.

The present invention also relates to a method of loeating a flare ofthe type which has just been described in position. which method ischaracterized by the fact that: the assembly of the caisson and the baseis formed and the cables serving for anchoring and guiding are coiled ina figure 8 on the base; the assembly comprising the base and the caissonare progressively immersed by known means; after having ballasted thebase when it is located at the bottom of the sea. a certain buoyancy isimparted to the caisson which is liberated from the base so that it canrise until the cables serving to anchor and guide it are subjected totension.

A preferably automatic connector is located beneath the caisson andconnected to the cable which anchors it and guides it. The lower end ofthe flexible tube is attached to the connector; the flexible tube isimmersed while permitting the connector to descend to the base; theupper end of the flexible tube is connected to the chimney of the flareand the lower end of the tube to the base; and the device regulating thetension on the cable is actuated to lengthen them and place the flexibletube under tension.

In a preferred embodiment of the invention. the connector which islocated at the lower end of the flexible tube is an automatic connectorwhich permits automatic engagement of the connector and thecorresponding connector on the base.

By operating in this way it is possible to locate the base on the bottomwithout having to use divers working at the depth of the sea floor.

When it is desired to change or inspect the flexible tube. tension isexerted on the anchoring cable and the connector is liberated from thebase which makes it possible to raise the tube upward after havingremoved the chimney from the flare.

The device according to the invention has the advantage of permittingthe semi-immersed flare to be easily mounted and maintained underconstant tension by the flexible tube which is a condition which is veryfavorable to its long life despite the movements to which it issubjected as a consequence of the agitation of the sea.

In a second embodiment of the invention several flexible tubes are usedwhich are located parallel to each other. each of which is equipped withanchoring and/or guiding cables which permit it to be located in placeas indicated above.

In the embodiment which comprises several flexible tubes the upper endsof the tubes are connected to the chimney by vanes which make itpossible to isolate certain tubes as bad.

In order that the invention may be better understood. severalembodiments thereof will now be described purely by way of illustrationand example with reference to the accompanying drawings. on which:

FIG. 1 schematically illustrates the first embodiment of thesemi-immersed flare according to the invention.

FIG. 2 illustrates a second embodiment of the invention:

FIGS. 38 schematically illustrate the successive steps in mounting thesemi-immersed flare according to FIG. 1.

FIG. 1 shows the chimney l of the flare resting on a caisson 2 whichhas. in the present case. an annular shape but may have a differentshape without thereby departing from the basic principles of theinvention.

At the level of the platform 3 of the caisson 2 the chimney l isconnected to the upper part 4 of the flexible tube 5 which. thanks tothe connector 6 located at its lower part, is connected to a connector(not shown) on the base 7.

This connector is connected to the tube which rests on the bottom of thesea 9.

Two cables 10 and II which may serve to anchor and/or guide are locatedbetween the caisson 2 and the base 7.

The drawings schematically show how the guide means 12 of the connector6 are attached to the cables 10 and 11.

FIG. I shows the semi-immersed flare in its operating position. Theflexible tube I is placed under tension by reason of the buoyancy of thecaisson 2 while the anchoring and/or guiding cables 10 and 11 are shownslack. It is also possible to hold a slight tension on the cables, thetorch being nevertheless anchored by the flexible tube.

The anchoring and/or guiding cables 10 and 11 are connected at theirupper part to the caisson 2 by means of a device which makes it possibleto vary their useful length in such a manner that by lengthening themthe tube I is placed under tension, whereas by shortening them andplacing them under tension, axial tension on the flexible tube 5 isrelieved, the buoy then being anchored by the cables.

Such devices may consist, for example, of winches which wind and unwindthe guiding cables 10 and 11 for a certain length or by hydraulic orpneumatic cylinders which move the point of attachment of the guidingcables 10 and I] with respect to the caisson 2 or by any otherconventional system.

It will be appreciated that under these conditions the flare subjectedto the action of the waves and the flexible tube 5 is placed undertension by the buoyancy of the caisson 2 which is favorable to thestrength and holding power of this flexible tube 5.

Moreover. the flexibility of the cable also permits the chimney to bedisplaced laterally even to tilt in re sponse to the movement of the seaor the wind.

In the embodiment of FIG. 2 a ballasting means 13 is schematicallyrepresented mounted on the lower part of the caisson 2 so as to impartthereto a stability which tends to hold the chimney I vertical or atleast to limit its inclination.

In the embodiment which is illustrated on FIG. 2, this figure shows thebase 7 which is connected to the caisson 2 by four cables for anchoringor guiding purposes 10, ll, 10'. 11' and by two flexible tubes 5 and 5',

Each flexible tube is provided with a base 6, 6' mounted on the guidecables by guide means 12.

In this embodiment the heads 4 and 4' of the tube 5 and 5 are connectedto the lower part of the chimney by vanes 14 and 14 which have beenshown schematically.

The cables serving for anchoring and/or guiding purposes are in thiscase also provided with means for varying their length in order topermit them to keep under tension or relieve from tension the tubes 5and 5.

The valves 14 and I4 make it possible to isolate one of the tubes so asto repair or replace it.

It is obvious that, according to the invention. it is possible to make asemi-immersed flare comprising more than two tubes, preferably regularlydistributed about the perihpery of the chimney of the flare.

A-description of how the flare may be placed in position over a greatdepth will now be given, for example, a depth of several dozen orseveral hundreds of meters or more.

FIG. 3 schematically shows how the base 7, supporting the caisson 1while the cables 10 and 11 are coiled in the form of a figure 8, isprogressively immersed by means ofa conventional device, for example, bymeans of a crane l5 equipped with antiramming means.

The duct 8 which is connected to the base may advantageously be alreadymounted thereon.

The assembly constituted by the base 7 and the caisson 10 is thenprogressively immersed until the base 7 rests on the sea floor 9.

When the base is fixed on the sea floor the caisson 2 is released, forexample, by means of a telemetric control device. Before carrying outthis operation and libcrating the caisson 2 one may, if desired, ballastthe caisson 7 either by filling it with water or by attaching thereto aheavy product which is sent down from the surface of the water through atube.

When the caisson 2 has reached its upper position, as may be seen inFIG. 5, the cables 10 and II are placed under tension by the buoyancy ofthe caisson 2.

The chimney is then mounted and this chimney I must be attached to thecaisson 2 by stays or fixed to the caisson 2 by any suitableconventional means. The ballast 13 is added beneath the caisson but doesnot form an integral part of the caisson and the flare.

In one variation of the caisson 2 the ballast l3 and the chimney l arefixed to each other and rest on the base 7, to which they are connectedby the cables serving for anchoring and guiding purposes and which arecoiled on the base. In this case the caisson. the ballast, the chimneyand the base are simultaneously and progressively immersed an then theassembly constituted by the caisson. the ballast and the chimney areraised toward the surface by uncoiling the cables, as has already beendescribed.

The connector 6 is then located at the end of the tube 5 and thisconnector is attached to the cables 10 and 11 by guide means 12. Byprogressively unrolling the tube 5, the base. which is guided by thecables 10 and I], is permitted to descend.

As shown on FIG. 5, the connector 6 is then attached to connecting meanspositioned on the base 7 and the connection may then be automaticallyeffectuated without using divers. This may also be done manually whenthe depth of the water is not too great to permit easy work by a diver.

The upper part 4 of the tube 5 is then connected to an appropriateattaching device located on the platform 3 of the caisson 2. It thensuffices to actuate the device for attaching the cables 10 and II to thecaisson 2 so as to slightly lengthen these cables so as to place thetube 5 under tension. which has the effect of relieving the tension onthe cables 10 and II or reducing the tension on the cables 10 and I I ifit is desired to retain a slight tension thereon. The flare is thenready to operate.

inspected or replaced by reversing this procedure. that is to say. byplacing the cables 10 and I] under tension while releasing the connector6 from the base 7 and raising the tube.

It will be readily understood that the tube 5 may be It is also possibleto proceed in the same way to inspect or replace the cables serving foranchoring or guiding purposes while the caisson is held by the tensionof the flexible tube.

It will be seen that the positioning of the flare according to theinvention as well as its maintenance can be carried out in a simple andeconomic manner.

In effect. most of the work carried out at the level of the caisson.that is to say. at a depth of immersion of the order of a dozen meters.is sufficient to protect the caisson from the action of the waves butnevertheless permits easy operation by divers.

The operations which must be carried out at the level of sea bottom maybe entirely automatized. if that is necessary. and if the bottom issufficiently deep so that work thereon is difficult. la the contrarycase. the work at the level of the base may be simplified when it ispossible to carry it out by submarine divers.

lt will of course be appreciated that the embodiments which have beenherein described have been given purely by way of illustration andexample and may be modified as to detail without thereby departing fromthe basic principles of the invention.

What is claimed is:

1. In a flare comprising a chimney which is mounted on a caisson havinga positive buoyancy connected to a base having a negative buoyancy andadapted to rest on the sea floor. the improvement comprising firstconnecting means in the form of at least one flexible water-tight tubelocated between said caisson and said base.

second connecting means in the form of at least two cables positionedparallel to each other and connecting said caisson to said base, and

means for placing either of said connecting means under tension so as torelieve the tension on the other.

2. Flare as claimed in claim 1 in which the flexible water-tight tubecomprises metallic reinforcements which resist radial tension andpresure and longitudinal tension as well as at least one water-tightsheath.

3. Flare as claimed in claim 1 in which the lower part of said at leastone flexible water-tight tube is provided with an automatic connectorwhich permits it to be automatically connected to at least oneconnection on the base.

4. Flare as claimed in claim 3 in which the connector on the base isitself connected by other ducts to the reservoir. or to the point atwhich the gas to be burned in the torch is separated.

5. Flare as claimed in claim 1 in which the caisson comprises ballastholding means.

6. Flare as claimed in claim 1 in which at least one ballasting deviceis mounted on the lower part of the caisson.

7. Flare as claimed in claim 1 which comprises a single flexible tubewhich connects the caisson to the base.

8. Flare as claimed in claim 1 which comprises several flexible tubeswhich are positioned parallel to each other between the caisson and thebase. each of which is accompanied by cables for anchoring and/orguiding it.

9. Flare as claimed in claim 8 in which the upper ends of the tube areconnected to the chimney by vanes.

1. In a flare comprising a chimney which is mounted on a caisson havinga positive buoyancy connected to a base having a negative buoyancy andadapted to rest on the sea floor, the improvement comprising firstconnecting means in the form of at least one flexible water-tight tubelocated between said caisson and said base, second connecting means inthe form of at least two cables positioned parallel to each other andconnecting said caisson to said base, and means for placing either ofsaid connecting means under tension so as to relieve the tension on theother.
 2. Flare as claimed in claim 1 in which the flexible water-tighttube comprises metallic reinforcements which resist radial tension andpresure and longitudinal tension as well as at least one water-tightsheath.
 3. Flare as claimed in claim 1 in which the lower part of saidat least one flexible water-tight tube is provided with an automaticconnector which permits it to be automatically connected to at least oneconnection on the base.
 4. Flare as claimed in claim 3 in which theconnector on the base is itself connected by other ducts to thereservoir, or to the point at which the gas to be burned in the torch isseparated.
 5. Flare as claimed in claim 1 in which the caisson comprisesballast holding means.
 6. Flare as claimed in claim 1 in which at leastone ballasting device is mounted on the lower part of the caisson. 7.Flare as claimed in claim 1 which comprises a single flexible tube whichconnects the caisson to the base.
 8. Flare as claimed in claim 1 whichcomprises several flexible tubes which are positioned parallel to eachother between the caisson and the base, each of which is accompanied bycables for anchoring and/or guiding it.
 9. Flare as claimed in claim 8in which the upper ends of the tube are connected to the chimney byvanes.